I'm seeing parser.fieldsToExpression(...).stringify() turn a day-of-week list like 1,3,5 into 1/2 …

I'm seeing parser.fieldsToExpression(...).stringify() turn a day-of-week list like 1,3,5 into 1/2 …: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). What the agent is asked, how it is graded, what it runs in, and its files.